There are three standard parts of spanners – the head, the profile and the shaft.
There could be one or two heads situated at both ends of the spanner depending on the particular type. One end of the spanner may have an open head with the other being a ring-type head. However there are also spanners that only come with the one head, with the other end simply being the handle.
Spanners that have two heads at both ends could have them be of different sizes. The head refers to the part of the tool that fits over the fastener.
The profile of the spanner is determined by the size and shape of the head. This is the part of the tool that actually makes direct contact with the head of the fastener. In some cases the profile may be able to be changed, as is the case with an adjustable spanner.
The profile size determines the tool size via the distance that is between the two flat sides. This is the same distance as the width over the top of a bolt or nut that has a corresponding profile, except in instances where the older standard sizes are still being used.
The sizes may be in metric or imperial units, with the latter often being written with the “AF” abbreviation that means “Across Flats” and shows that the size is the width between the profile’s flat sides, as indicated above.
Another possible measurement is the width between the profile’s two opposing corners, which would be indicated by the abbreviation “AC” which stands for “Across Corners”, but this is not used in the definition of the size of spanners.
The shaft is the name given to the handle of the spanner. The shaft behaves as a lever through which greater force can be produced, and the longer the handle is, the more torque will be produced although there is obviously a limit to how long the handle can actually be.
The length of the handle is actually dependant on the size of the profile, with larger fasteners requiring bigger forces in order to rotate either clockwise or anti-clockwise.
The shaft length can be extended to a certain extent with the use of the likes of a pipe, but care needs to be taken to ensure this is not overdone or it will cause damage to fastener and spanner alike.
The majority of spanners come with shafts that are of a length that they can still be held by one or at most two hands, although some come with a stubby design that is intended to allow them to have access to smaller spaces. It is important to remember that although this spanner type can be useful they do not offer much in the way of leverage.
There are many different types of spanner available on the market today, but the parts of these tools are almost always the same.